In some electric motors, a brush holder is placed between a motor main body side housing (a yoke housing) and a speed reducer side housing (gear housing). The brush holder includes a holder member and a base member. The holder member holds brushes. The base member includes a connector and is installed to the holder member. One such a motor is disclosed in Japanese Unexamined Patent Publication No. 2009-011076A. In this type of motor, in order to install the brush holder to the yoke housing, a positioning structure needs to be provided to axially position the holder member relative to the yoke housing. In the case of Japanese Unexamined Patent Publication No. 2009-011076A, an abutting portion (referred as a stepped portion in this Japanese Unexamined Patent Publication) is formed in an inner peripheral wall of the yoke housing. One axial side part of the holder member is axially abutted against the abutting portion, and the other axial side part of the holder member is axially abutted against the base member. In this way, the holder member is axially positioned.
However, in the case of the above-described motor, the abutting portion, which is formed in the yoke housing, adds a complexity to the structure of the yoke housing.